Method of fastening



April 20, 1965 M. R. SIMMONDS METHOD OF FASTENING 2 Sheets-Sheet 1Original Filed Aug. 18, 1958 INVENTOR.

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United States Patent 3,178,810 METHOD OF FASTENING Milo R. Simmonds, 34Hirschfield Drive, Williarnsville, NY.

Original application Aug. 18, 1358, Ser. No. 755,524, now Patent No.3,061,054, dated Oct. 30, 1962. Divided and this application Oct. 29,1962, Ser. No. 233,843

1 Claim. (Cl. 29-456) This application is a division of my copendingapplication Serial No. 755,524, filed August 18, 1958, now Patent No.3,061,054.

This invention relates generally to the fastener art, particularly asapplied to double wall structures and structural sandwiches of the typehaving relatively high strength skins or laminae spaced apart by arelatively weak core. More specifically, this invention is concernedwith the method of providing spacer means between pre-assembled highstrength laminae which receive fastening means therethrough.

Structures of the above mentioned type offer many advantages and have awide area of application, but fastening to such sandwiches presents aserious problem because the stabilizing core cannot carry the fasteningload and it is necessary to transfer such fastening loads to therelatively high strength laminae in order to avoid distorting the core.

Accordingly, it is a primary object of this invention to provide amethod enabling fastening to such structures wherein the fastening loadis transferred directly to the relatively high strength, stressedlaminae wihout crushing the relatively weak core material and/ordeforming the skin.

Further, it is an object of this invention to provide a method ofinserting a spacer member in the pre-assembled sandwich structure, whichmethod is characterized in one aspect thereof by rotating the spacermember about substantially its lengthwise axis to thread it through anopening in one lamination, until the spacer member extends partiallytherethrough into the space between the laminations, and then rollingthe spacer member in the opposite direction about the periphery of theopening, in a manner causing the spacer member to continue threadingthrough the opening until it is inserted entirely between thelaminations.

Other objects and advantages of the invention will appear from thedescription hereinbelow and the accompanying drawing wherein:

FIG. 1 is a perspective view showing a portion of a structural sandwich;

FIG. 1A is a view similar to FIG. 1 but showing the top lamina removedfrom the structure to illustrate the stabilizing core;

FIG. 2 is a view similar to FIG. 1 but illustrating the first step inthe method;

FIG. 2A is a view similar to FIG. 1A and illustrating clearly theprovision of the drilled hole through both of the skin elements orlaminae;

FIGS. 3 and 3A illustrate the step of cleaning out the core material inthe region of the openings through the skin elements to provide workingspace;

FIGS. 4 and 4A illustrate a tool which may be used in the methodaccording to the present invention; and

FIGS. SA-SF illustrate various sequential steps in the assembly method.

Referring now more particularly to FIGS. 1 and 1A, there is shown astructural sandwich 1d of conventional construction, which per secomprises no part of my in vention. This sandwich comprises a pair ofhigh strength skins or laminae 12 and 14, bonded to and spaced apart bya low density core 16, substantially as is shown. The

3,178,810 Patented Apr. 20, 1965 ice sandwich comprising the parts 12,14 and 16 can be of any known construction, or variation thereof, myinvention being directed to the method whereby fastening or attachmentloads may be directly transferred to the laminae 12 and 14 withoutcrushing the core 16 or deforming the laminae or skin. To accomplishthis end, a spacer indicated generally by the reference character 18 asis shown in FIG. SP is ultimately inserted between the laminae 12 and 14and the spacer 16 is of such construction that when disposed in theposition shown in FIG. 5F, the spacer has a solid length which issubstantially equal to the spacing between the inner surfaces of thelaminae 12 and 14. In this fashion, the fastener such as is illustrateddiagrammatically at 20 in FIG. 5F when inserted through the sandwichassembly 10 will not tend to crush the core 16 or deform the skinelements 12 and 14.

In the method of inserting the spacer as aforementioned, the sandwich 10is first drilled as is illustrated in FIGS. 2 and 2A so as to provideopenings 22 and 24 in the top and bottom skin elements 12 and 14thereof. It will be appreciated that the openings 22 and 14 are alignedas is shown clearly in FIG. 5F so as to readily receive the fastenerelement 20 therethrough. After the holes 22 and 24 have been drilled,the core material 16 is removed within a sufiicient area therearound toprovide room for the spacer 18. Thismay be accomplished by means of atool such as the back spotface tool 26 illustrated in FIGS. 3 and 3A.The shank 28 of this tool is of less diameter than the openings 22 and24 and terminates at one end in a bit or blade portion 30 extendinggenerally at right angles thereto, the bit having a cutting edge 32 atits outer end and cuting edges 34 and 36 along its top and bottom edgesrespectively. To enable insertion of the blade or hit portion 30, thediagonal distance across the heel thereof is less than the diameter ofopenings 22 and 24 and any suitable handle mechanism (not shown) enablesthe operator, after inserting the tool as is illustrated in FIG. 3A, torotate the shaft 28 about its axis while raisin and lowering the bit 31)between the laminae 12 and 14 so that a generally cylindrical piece ofcore material is removed, substantially as is shown in FIG. 3A. While itis not necessary that all of the material in such cylinder be removed,it is desirable to remove the glue or resin from the underside of bothskin sheets 12 and 14 so as to permit the spacer member to seat properlyagainst the opposed surfaces of the skin or laminae 12 and 14.

The spacer 18 is threaded into the sandwich ultimately into the positionshown in FIG. 5F by means of a tool indicated generally by the referencecharacter 40 in FIGS. 4 and 4A. This tool comprises an elongate shaft 42which is of a length exceeding the length of the spacer member 18 so asto extend therethrough and which is of a diameter less than thedifference between the diameter of the openings 22 and 24 and the widthof the wire from which the spacer element 18 is formed. The shaft 42 isprovided at one end thereof with a handle or head 44 and which head orhandle 44 is rotatably received on the upper end of the shaft 42. Theunderside of this head 44 is provided with a counterbore which isinternally threaded to receive the upper end of the spacer 18 so thatwhen in the position shown in FIG. 4A, the spacer is effectivelyclutched or locked to the head 44. The lower end of the shaft or shank42 is provided with an enlarged bulbous portion 46 which has a diameterslightly less than the inside diameter of the spacer 18.

For assembling the spacer 18, the same is slipped onto the shaft 42 andthreaded into the handle or head 44 substantially as is shown in FIG.4A. Then, the shaft 42 is inserted through the aligned openings 22 and24 as is illustrated in FIG. 5A and caused to bear against one side edgeof the upper opening 22 and the opposite side edge of the other opening,as shown, whereafter the handle or head .44. isrotated in a directioncausing it. to clutch with the spacer 18 and thread the same partiallythrough the upper- 1 most opening 14 with this action being continued,for example, until the spacer-18 is in approximately the posi tionillustrated in FIG. 5B. The spaceri18 can be inserted ,in this manneranywhere from part .of a turn to all the end portion 46 is within theconfines of the lower openv ing 24. The head or handle 44 is then swungin the opposite direction in an orbit about .the' centerline of theopenings while maintaining contact between the shaft or shank 42 andopposed peripheral side-edges-of the open- .ings, as is illustrated inFIG. 5D. Upon so doing, the

shank 42 rolls around the periphery of the upper opening entrypoint'whichis further and further up the spacer. Due to the frictioninherent inthe above action, the spacer 18 rotates very slowly in thesame direction as the insert,- a

ing tool is swung.

Thus, after being rotated about its axis in one direction until it ispartially threaded through the upper opening 22, the spacer 18 is swunginthe opposite direction in a generally conical path about thecenterline of the opening. This action is continued until the spacer 18.is entirely between the two laminae 12 and 14 of thesandwich,

rolls the spacer through and several continued rotations of'the shaft 42serve to center both the'up-per and lower ends of the spacer withrespect to the openings 22 and 24. Further, as the inserting tool isremoved from the openings, the bulbous lower end portion 46 thereof-further assures centering of the spacer 18, and the spacer is ready to'have a bolt, rivet or other fasteningmeansZi) inserted'therethrough forattach- .ing a member to the sandwich.

' It is to be understood that certain changes and modifieations asillustrated.and'described may be made without departing from the spiritof the invention or the scope of the following claim. p a

I claim: i

The method of inserting aspirally wound spacer member between spacedlaminae of a pre-assembled structural member, where the laminations havealined openings therethrough of lesser diameter than the outer diameterof thespacermember, which method comprises, rotating the spacer memberabout a'shaftextending bteween the laminae :from one edge of one openingto the opposite edge of the other opening until the spacer member ispartially threaded throughone opening into the space between thelaminae, and then swinging said'shaft in the opposite direction whilemaintaining contactbetweenopposed peripheral edges of the spacedopenings whereby the shaft the opening and between the spaced laminae. a

References Cited by the Examiner UNITED STATES PATENTS 2,563,976 8/51Torosian 29428 X WHITMORE \VILTZ, Primary Examiner. CHARLIE T. MOON,Examiner.

